Digital contents maintain the same quality as original contents even after being copied several times, unlike analog contents. When digital contents having such a property are propagated via an Internet communication medium, copy contents having the same quality as the original contents may spread rapidly and without limit. Thus, contents owners (for example, Hollywood movie producers in the U.S.) who produce contents by investing huge capital and great effort are reluctant to digitize or commercialize their own contents over the Internet. Such a climate brings about a disadvantage in that high quality contents are not supplied to contents consumers (users).
To solve this problem, as a method of encrypting and distributing or circulating digital contents, selling use authority and decryption keys of the digital contents to users, and reproducing the digital contents, a digital rights management (DRM) technology of providing users with different use authority of digital contents and protecting rights of digital contents has been developed.
The DRM technology is implemented by using an application program by itself, or by controlling an input and output operation of the application program from outside of the application program.
To implement the DRM technology by using the application program by itself involves the application program by itself preventing access to digital contents except to authorized users. This is the most stable method but the number of application programs supporting this is limited, and DRM technologies implemented by application programs differ from each other and are limited, and thus DRM technologies are limitedly unified and limitedly supplied.
Furthermore, technologies (applications filed by our firm (Korean Patent Application Nos. 2002-0072906 and 2007-0086361), which use a hooking technique by controlling an input and output operation of an application program from outside of the application program, implement a DRM function but are closely related to an implementation of the application program, which lowers stability since these technologies are sensitive to a version upgrade patch of the application program, and are very costly in terms of development.
Therefore, to solve these problems, an apparatus and method for enhancing stability and compatibility of the DRM function are required.